Styrene resins have been widely used for plastic containers because of superior formability. Taking into account problems such as effects on the environment, vinyl chloride resins have recently been replaced by styrene resins in the field of plastic containers, and a so-called impact-resistant styrene resin composition obtained by mixing a styrene resin with a thermoplastic elastomer has been widely used in forming sheets obtained by vacuum molding and press forming the styrene resin sheets. However, increase in the content of the thermoplastic elastomer in an impact-resistant styrene resin composition leads to reduction in the rigidity of the forming sheet, although the impact resistance thereof is enhanced, and makes the resulting molded article subject to deformation when high loads are applied from the outside, thereby tending to cause damage of goods contained inside in the case of a container for packing the goods. On the other hand, when the content of the thermoplastic elastomer in the impact-resistant styrene resin composition is decreased, the molded article has low impact strength, although the rigidity is enhanced, and thus the molded article is likely to crack, fracture, and break. Therefore, there have been attempts to achieve good balance between the rigidity and the impact resistance, which conflict with each other. For example, there has been known a transparent impact-resistant resin composition comprising a styrene-butadiene block copolymer containing 65 to 85% by weight of a styrene block, and a styrene-butyl acrylate copolymer, and a styrene-butadiene block copolymer containing 10 to 50% by weight of a styrene block (see, for example, Japanese Patent Application, First Publication No. Hei 7-309992).
Although the transparent impact-resistant resin composition can impart excellent rigidity and excellent impact resistance to a molded article of the composition, the resulting molded article has insufficient surface impact strength, and various secondarily formed articles such as blister packs, carrier tapes and containers for food obtained by secondarily forming a forming sheet are likely to break and crack by vibration upon dropping or transportation when containing goods.